This application is related to and claims priority, under 35 U.S.C. xc2xa7119, from Japanese Patent Application No. 11-150258, filed on May 28, 1999, the entire contents of which are hereby incorporated by reference herein.
1. Field of the Invention
The present invention relates to an outboard motor having an engine to which a starter motor and an oil filter are mounted.
2. Discussion of Background
In general, an engine of an outboard motor is mounted such that a crankshaft is directed vertically uprightly, and the engine comprises a crankcase directed forward (towards a hull in a mounted state of the outboard motor), a cylinder block disposed to a rear portion of the crankcase and a cylinder head disposed to a rear portion of the cylinder block. When the engine is of a four-stroke-cycle in-line multi-cylinder type, an intake system is disposed on one side of the engine, and an exhaust system, an electrical equipment box, an oil filter and the like are disposed on the other side of the engine as shown in Japanese Patent Laid-open Publication No. HEI 10-176541. A starter motor for starting the engine is disposed in a central portion of a front surface of the crankcase. By disposing each of these parts in accordance with such a layout, a space in a small engine cover of the outboard motor can be utilized effectively, and the balance of weight between the left and right sides of the outboard motor can be achieved.
Further, for fixing the starter motor, there is a fixing structure as shown in FIGS. 9 and 10 in which fixing pieces 102 and 103 projecting from a peripheral surface of a starter motor 101 are fastened to starter fixing bosses 105 and 106 integrally extending from a crankcase 104 from the front side by fixing bolts 107, and an exclusive mounting bracket is omitted to reduce the number of parts. In this arrangement, the axial direction of each fixing bolt 107 is horizontal direction.
However, according to the above structure, since the oil filter is disposed on a side surface of the engine, when the outboard motor is mounted to a hull and it is difficult to touch the oil filter with a hand and also difficult to exchange the oil filter, and maintenance performance of the engine is poor. On the other hand, electric equipments and the like are disposed below the starter motor in many cases, but since this position is located below the engine, it is not preferable in terms of waterproofing. Further, since the starter motor largely projects to the central portion of the front surface of the crankcase, forward and backward length of the engine is increased.
On the other hand, if the starter motor 101 is fixed to the crankcase 104 as shown in FIGS. 9 and 10, since the axial direction of the fixing bolt 107 does not coincide with the axial direction of a crank bearing 108 formed on the crankcase 104, the crank bearing 108 and a screw hole of the fixing bolt 107 must be formed separately. As a result, the relative positional precision of the starter motor 101 with respect to the crankshaft will be ensured, and there is an adverse possibility that engagement backlash between a pinion gear of the starter motor 101 and a ring gear of a flywheel which is mounted at an upper end of the crankshaft after the engine is assembled becomes improper.
The crankcase 104 is formed at its outer surface with a large number of parts such as fastening bosses for fastening and fixing the crankcase 104 itself to the cylinder block and also formed with part fixing bosses for disposing other parts. Therefore, it is difficult to freely set and design upper and lower positions of the starter fixing bosses 105 and 106. Further, in the case of the fixing structure shown in FIG. 9, if the heights of the left and right starter fixing bosses 105 and 106 are slightly inaccurate, torsion or bending stress is applied to the fixing pieces 102, 103 of the starter motor 101, and service life of the fixing pieces 102, 103 may therefore be shortened. On the other hand, in the case of the fixing structure shown in FIG. 10, since a working direction of the screw hole of the fixing bolt 107 is quite different from those of many other holes, working cost will be increased.
As described above, since there are many constraints for mounting the starter motor, in order to dispose the starter motor at a desired position, it is necessary to form the fixing pieces of the starter motor into complicated shapes. However, this results in increase in cost for producing the starter motor, and results in reduction in general utilization. In addition, when the starter motor is mounted to the crankcase, it is necessary to hold the heavy starter motor with one hand and to fasten the fixing bolt with the other hand at the same time, thus the operability of the outboard motor being made poor.
The outboard motor of the present invention has been invented to solve the above problems, and it is a first object of the invention to provide an outboard motor including an improved arrangement of a starter motor and an oil filter for effectively utilizing a space, for easily exchanging the oil filter from a hull side and for enhancing the maintenance performance of an engine.
Another object of the present invention is to provide an outboard motor capable of shortening a forward and backward length of the engine to make the outboard motor compact.
A further object of the present invention is to provide an outboard motor capable of enhancing the relative positional precision of the starter motor with respect to a crankshaft, enhancing the flexibility of mounting position of the starter motor and enhancing the mounting operation of the starter motor.
A still further object of the present invention is to provide an outboard motor having an improved outer appearance and providing an improved fixing structure for the starter motor and others.
These and other objects can be achieved according to the present invention buy providing an outboard motor comprising:
an engine disposed of a vertical type including a crankcase in which a crankshaft extends vertically perpendicularly, a cylinder block disposed rear side of the crankcase, and a cylinder head disposed rear side of the cylinder block in a usable mounted state of the outboard motor;
a starter motor mounted to a front surface portion of the crankcase; and
an oil filter mounted to the crankcase at a portion below the starter motor.
In preferred embodiments, the starter motor and said oil filter are disposed so as to be deviated sideways in locations with respect to an axis of the crankshaft as viewed in a front view.
The crankcase is provided at an upper portion thereof with a starter fixing boss projecting horizontally and the starter motor is fastened to the starter fixing boss by means of fixing bolt which is directed in a perpendicular direction. The starter motor is provided with a fixing flange which spreads in a horizontal direction and the fixing flange is mounted on the starter fixing boss by means of the fixing bolt.
The crankcase is provided with a starter holding boss located below the starter fixing boss, a holding band is fixed to the starter holding boss, and a lower portion of the starter motor is held between the holding band and the starter holding boss. An electrical element such as relay is disposed between said starter fixing boss and said starter holding boss, and at least one of the starter fixing boss and said starter holding boss is integrally formed with a fixing boss for fixing the electrical element.
According to the outboard motor of the structures mentioned above, it is possible to dispose a starter motor and an oil filter while efficiently utilizing a space, to easily exchange the oil filter from a hull side and to shorten the forward and backward length of the engine, making the outboard motor compact.
It is possible to enhance the relative positional precision of the starter motor with respect to a crankshaft and to enhance the flexibility of the mounting position and the mounting operation of the starter motor. The starter motor can reliably be held with a simple structure.
Still furthermore, it is possible to dispose other parts around the starter motor while utilizing a space efficiently and enhancing outer appearance, to enhance the strength of part fixing bosses to enhance the resistance to vibration and to reduce the weight.
The nature and further characteristic features of the present invention will be made more clear from the following descriptions made with reference to the accompanying drawings.